. >> there are troubling new signs out of syria. intelligence suggests syrian forces may be preparing to use chemical weapons on its own people. a u-s official says... according to intelligence obtained over the weekend... syrian forces began mixing two chemicals needed to make deadly sarin gas. president obama issued a stern warning to syrian president bashar al-assad. >> i want to make it absolutely clear to assad and those under his command -- the world is watching. the use of chemical weapons is and would be totally unacceptable. >>pam: u-s officials are concerned that with fighting moving closer to damascus, the assad regime may be getting desperate and could use chemical weapons to try to crush the rebellion. secretary of state hillary clinton says if assad goes down that road... there will be consequences. >> this is a red line for the united states. i'm not going to telegraph in any specifics what we would do in the event of credible evidence that the assad regime has resorted to using chemical weapons against their own peop